Jean Marsh still remembers vividly the day she started filming the first new episode of "Upstairs Downstairs," a revival of the signature 1970s British series that premieres Sunday, April 10, on PBS' "Masterpiece Classic" (check local listings).

Reprising her Emmy-winning role as Rose Buck, the actress, now 76, was standing in a re-creation of the stately London home set where she had worked for five seasons when she received some spectacularly unnecessary advice from her director.

"He said to me, 'Now, when you walk into the hall, don't forget that this is the house where you were the happiest, so you must be moved,' " Marsh recalls. "And I thought, 'My God, do you think I'm not moved? I'm moved as Rose, and I'm moved as Jean.' I walked into that replica of the hallway, and I could hear voices. It was just breathtaking. I said, 'You'd better not say that to me again, or you'll just have me crying all the time, and I think the audience should cry, not me.' "

If viewers do shed some tears, they will be happy ones. The original "Upstairs" has remained a fan favorite in the 40-year "Masterpiece" pantheon. Marsh, who co-created that original series with close friend Eileen Atkins ("Cranford"), says several interested parties have approached the two women since the first series ended its run more than three decades ago. Broadway composer Burton Lane ("On a Clear Day You Can See Forever") and lyricist Sheldon Harnick ("Fiddler on the Roof") even took a stab at turning it into a stage musical.

But it was only after "Cranford" screenwriter Heidi Thomas, who fell in love with "Upstairs" as a little girl, decided to tackle a reboot of the series that things started to move forward.

As the new episodes open in 1936, 165 Eaton Place is about to get a new family in residence: Sir Hallam Holland (Ed Stoppard, son of playwright Tom), a diplomat returning from a stint in Washington, D.C., and his wife, Agnes (Keeley Hawes, "Wives and Daughters"), soon joined by his recently widowed mother, Lady Maud (Atkins), and Agnes' headstrong younger sister, Lady Persie (Claire Foy, "Little Dorrit").

Originally hired by Agnes to assemble a household staff, Rose eventually is pressed into service as the housekeeper of the residence, joined by Mrs. Thackeray (Anne Reid, "Bleak House"), the cook, and Mr. Pritchard (Adrian Scarborough, "Cranford"), the butler.

"In Britain, 1936 was known as 'the year of three kings,' because George V died in January, Edward VIII came to the throne and then abdicated in December, giving way to George VI," Thomas explains of the new historical setting. "It was just a year of enormous change. It was a crucial point in European history, with the rise of fascism, and it also gave us a chance to look at what was happening in the working class, and the riot in Cable Street, when the ordinary British working man rose up against that specter of fascism."

Thomas pitched the idea to Atkins during a long flight back to England following a U.S. press tour for "Cranford" and had an informal deal worked out by the time their plane landed. Marsh, however, admits to being a trifle wary when she heard about the proposed project.

"I was instantly nervous," she says. "I was anxious about the past and the possibility of letting so many people down. Not just me and Eileen, but also all the actors who were now dead. I thought it probably was a good idea, but I wasn't sure. When I actually sat at the first read-through with all of the actors around me -- I sat between Mrs. Thackeray the cook and Mr. Pritchard the butler -- and they were so fabulous that I knew both Gordon Jackson and Angela Baddeley (who played butler Mr. Hudson and cook Mrs. Bridges in the original) would approve of them. That's when I thought, 'It's going to be all right.' "

Actually, it's quite a bit more than just all right. The three episodes that make up this initial miniseries, with the happy possibility of more to follow, are a triumph, perfectly recapturing the spirit of the original yet picking up the storytelling pace to appease modern attention spans. As Marsh's first impression reflected. Reid and Scarborough not only stand up to fond memories of Baddeley and the Emmy-winning Jackson but they also make indelible impressions of their own as Eaton Place's new cook and butler. And Atkins, whose busy stage career kept her from appearing in the original "Upstairs," is a crusty delight as Lady Maud.

Rebecca Eaton, the American executive producer of "Masterpiece," is confident fans will find that the new series was well worth the wait.

"I think I have been looking for a new 'Upstairs Downstairs' from the moment I walked into this office and took this job 25 years ago," says Eaton, who ranks the original "Upstairs" in the all-time top five of "Masterpiece" offerings. "It's the perfect sequel, and we've all dreamed about it."

In fact, she's hoping that the new "Upstairs," which the BBC is releasing on DVD April 26, will remind viewers of how much pleasure "Masterpiece" has given them over the years, enough to consider joining the Masterpiece Trust, a funding initiative started in honor of the series' 40th anniversary. In return for a $25,000 contribution, supporters receive on-screen recognition on at least three new "Masterpiece" programs, with a significant portion of their donations going directly to their local PBS stations.